Actuator for controlling inclination of treadmill and inclination control device of treadmill

ABSTRACT

The present invention provides an inclination control device of a treadmill comprising: a pair of support members pivotally connected with at least one first hinge at the track part for extending from the track part to the ground; a pair of housings having a housing hinge respectively for being pivotally connected with each of the second hinge at the support members, and having female thread; a pair of screw rod engaging respectively with the female thread of each of the housing so as to be extruded from or inserted into by relative rotation therebetween; a pair of driving pulleys combined with each of the screw rod for rotating together with the screw rod; a belt engaging with the driving pulleys; a pinion engaging with the belt for transmitting a driving force via the belt to the driving pulleys; a motor for letting pinion rotate; and a bracket for rotatably fixing the pinion and the driving pulleys, and having a pair of bracket hinges on its both sides to be pivotally combined with each of the third hinges of the track part, whereby the first hinge, the second hinge and the third hinge form a three-linked structure so as to stably support the impact and/or load from a user&#39;s running in addition to enhance durability and to save the manufacture cost.

BACKGROUND

1. Field of the Invention

The present invention relates to a treadmill, more particularly, to anactuator for stably controlling an inclination of the track part of atreadmill and an inclination control device of a treadmill.

2. Discussion of Related Art

A treadmill known as a running machine is widely used indoors such as athome or in a sports center because it allows a user to effectivelyexercise by working or running on its endlessly rotating track belt evenin the narrow space. In view that a user can exercise indoors usingtreadmill even in the cold winter, the demand for treadmills is recentlydrastically increasing due to the advantages of its safety andconvenience because.

By using a treadmill, the user thereof can strengthen thecardiopulmonary function and muscles of legs, and can control weight byconsuming calories efficiently while running or walking on thetreadmill. To maximize this exercise effect, a treadmill with aninclination control device came to be lately produced.

More specifically, a treadmill generally comprises a track part on whichuser put their feet for running or walking, and an inclination controldevice for supporting the track part and to control the inclination.

As illustrated in FIGS. 1 and 2, the conventional treadmill comprises atrack part 10 on which user run or walk, a support part 20 located at abottom of the treadmill for controlling the inclination of the trackpart 10 while sustaining the load or impact transmitted from the trackpart 10.

The track part 10 has a support frame 11 which upholds weight of user; abelt rotating endlessly, which enables a user to run or walkcontinuously on the upper side of the track part 10; a pair of rollers13 supporting both sides of the belt 12; a motor 14 as a driving unitfor driving making one of the rollers 13 rotate; and connection part 15linked with the actuator 30.

The support part 20 includes a base frame 21 installed on the ground,and a support member 22, having its one end fixed to a base frame 21 andthe other end 22 a pivotally connected to a track part 10.

The actuator includes a extendable rod 32, of which one end 32 a ispivotally connected to a link member 15 of the track part 10, and ofwhich the other end is pivotally connected to a base frame 21; and adriving part 31 to control the length of the extendable rod 32 byextending or contracting the extendable rod 32.

The above conventional treadmill controls its inclination of the trackpart 10 by means of extending or contracting the extendable rod in thedirection of 30 a. In this case, the load or impact of user isconcentrated on the part where user put their foot apart from the otherend 22 a of a fixed member by d1. That is, The load and/or impact isconcentrated on the front part of the track part 10, and thus the loadFa of the actuator 30 will be obtained by the following equation incondition that the track part 10 is parallel to the ground.Fa′=F  Equation 1

In general, since d2 is designed smaller than d1, the load Fa′ appliedon the actuator 30 is calculated by user's load F₁ amplified by d1/d2.Besides, the actuator get more moment due to user's load F₁ generatedfrom exercise on the track. The conventional treadmill accordingly needsa big actuator to endure the load and it result in an unnecessaryincrease of manufacture costs and power consumption.

Also, it is not desirable to install a big actuator in the narrow spacebetween a track part 10 and a base frame 21, from view that a user feelssafe when the distance between the base frame 21 and the track part 10is as short as possible. As a solution for this problem, it can beconsidered that the actuator 30 is installed at both sides of the trackpart as a pair. However, if two actuators 30 are not exactly controlledwith the same extended or the same contracted length, it causes to havea problem that track part 10 is widthwise inclined even by the smallamount, whereby the user feels unstable and uncomfortable.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above and/or otherproblems, and it is an object of the present invention to provide withan actuator for controlling an inclination of the track part of atreadmill, which is capable of stably controlling the inclination of thetrack part by simultaneously contracting or simultaneously extending apair of extendable rods.

Another object of the present invention is to provide an inclinationcontrol device of a treadmill, which minimizes the load and moment onthe extendable rod of the actuator for controlling the inclination ofthe treadmill thereby enhancing durability as well as efficientlyreducing the manufacturing cost.

In order to achieve the above objects and another aspect of the presentinvention, the present invention provides an actuator for controllingthe inclination of the track part of a treadmill comprising: a drivingunit; a pinion rotatably driven by the driving unit; a belt formed totransmit the driving force from the pinion; a pair of driving pulleysengaging with the belt so as to receive the driving force from thepinion; a pair of screw rod combined with each of the driving pulley forrotating together with each of the driving pulley; and a pair ofhousings having female thread for engaging with each of the screw rod,whereby a pair of screw rods are simultaneously extruded from orsimultaneously inserted into each of the housing by the same length.

This is intended to control a pair of extendable rods including thescrew rods and the housings to be extended or contracted by the sameamount based on that the driving force from the driving unit istransmitted via the belt to a pair of the driving pulleys so that a pairof the driving pulleys rotates by the same amount.

Herein, at least one idler pulley engaging the belt is additionallyincluded thereby obtaining the higher wrapping angle of the pinionsurrounded by the belt. Therefore, the friction between the pinion andthe belt is increased, and the driving force can be transmitted to adriving pulley without any loss.

Periodical grooves are formed on the outer sides of the pinion, theidler pulley and the driving pulley, and also, the periodicalprotuberances engaged with the grooves are formed so as to thoroughlyremove any slip between the belt and the pulleys due to the increase ofthe friction, thereby precisely controlling the screw rod'sdisplacement.

It is effective to further comprising: a bracket for rotatably fixingthe pinion, the idler pully, and the driving pulleys as one module;bracket hinges formed on both end sides the bracket to be pivotallycombined with the track part of a treadmill; and housing hinges formedat each of the housings, whereby the actuator can be easily combinedwith a treadmill which realizes stable control of the inclination of thetrack part.

Meanwhile, the actuator for controlling the inclination of a treadmillcan use chain or gear instead of the belt as a power transmission meansin order to embody the same function.

That is, the treadmill can comprise a driving unit; a pinion rotatablydriven by the driving unit; at least one pair of intermediate gearformed to transmit the driving force from the pinion; a pair of drivinggears engaging with the intermediate gears so as to receive the drivingforce from the pinion; a pair of screw rod combined with each of thedriving gear for rotating together with each of the driving gear; and apair of housings having female thread for engaging with each of thescrew rod, whereby a pair of screw rods are simultaneously extruded fromor simultaneously inserted into each of the housing by the same length.

Herein, the intermediate gears can be plural at one side between thepinion and the driving pulley because it is necessary to install thedriving pulleys apart from the pinion in the narrow and long bracket.

On the other hand, the present invention provides with an inclinationcontrol device for a treadmill having at least one track partcomprising: at least one extendable rod pivotally connected with atleast one second hinge which moves together with the support member, andpivotally connected with a third hinge of the track part which islocated apart from the first hinge at the track part; wherein, theinclination of the track part is controlled by the extension or thecontraction of the extendable rod.

That is, the first hinge, the second hinge and the third hinge formthree-link structure, thereby securely support the track part. Althoughthe actuator is located in the front area of the track belt on whichuser put their feet, as the load and/or impact from a user is notconcentrated on the screw rod of the actuator because three elements(i.e., the track part, the support member, and the screw rod with thehousing) make up a three-link mechanism, the screw rod can be designedto be smaller diameter or to be a smaller size for obtaining therequired durability, thereby realizing the small-sized actuator andsaving the manufacturing cost.

It is desirable to include a traverse member to connect between a pairof the support members for obtaining stability.

Also, the second hinge is located at the traverse member so as to easilypivotally combine the extendable rod (more specifically, housing) withthe traverse member, thereby achieving the lower manufacturing cost.

It is effective for each roller to be attached at the end of the supportmembers contacted with the ground, thereby reducing friction between thesupport member and ground when the inclination of the track part iscontrolled.

When the length of the support member is assumed as L, it is desirablethat the second hinge is located in 0.1 L or 0.5 L from one end of thesupport member contacted with ground. It means that the second hinge isformed near to ground so as to reduce the load applied on the screw rod.

The gear can be used as a means of transmitting power from the driveunit for controlling the inclination of the treadmill.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other objects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofpreferred embodiments, taken in conjunction with the accompanyingdrawings of which:

FIGS. 1 and 2 are views illustrating an inclination control device of aconventional treadmill, in which:

FIG. 1 is a side view illustrating a structure of inclination controldevice of treadmill;

FIG. 2 is a side view showing the reaction force on the inclinationcontrol device of FIG. 1 as a user exercises thereon;

FIGS. 3 to 7 are views illustrating an actuator for controlling aninclination of the track part of the treadmill in accordance with oneembodiment of the present invention;

FIG. 3 is perspective views of part of the actuator when the extendablerod thereof is contracted.

FIG. 4 is perspective views of part of the actuator when the extendablerod thereof is extended.

FIG. 5 is a perspective view of the actuator adding a hinge bracket intothe part of the actuator of FIG. 3;

FIG. 6 is a perspective view of the actuator from another view;

FIG. 7 is a plane view of FIG. 5;

FIG. 8 is a schematic view illustrating a structure of an actuator forcontrolling an inclination of the track part of the treadmill inaccordance with another embodiment of the present invention;

FIGS. 9 to 12 are views illustrating an inclination control device usingthe actuator shown in FIG. 5 for a treadmill in accordance with oneembodiment of the present invention;

FIG. 9 is a perspective view illustrating the treadmill when theinclination of the track part is high position;

FIG. 10 is a perspective view illustrating a structure of the treadmillwhen the inclination of the track part is low position;

FIG. 11 is a perspective view illustrating a structure of treadmillwithout a driving cover when the inclination of the track part is lowposition;

FIG. 12 is a side view of the treadmill shown in FIG. 10; and

FIG. 13 is a FIG. to explain the three-linked truss structure fordiverging the load from walking or running of a user.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, an actuator for controlling an inclination of a treadmillaccording to a preferred embodiment of the present invention will bedescribed.

As illustrated in FIGS. 3 to 7, the actuator 130 for controlling theinclination of a treadmill in accordance with one embodiment of thepresent invention comprises a driving unit for generating andtransmitting the driving torque; and a pair of extendable rod 140 whichcan be extended or contracted in its length by using the powertransmitted from the driving unit.

The driving unit has an actuator motor 131 generating rotating force; atransmission 132 for reducing the rotating speed of a actuator motor131; a pinion 133 rotatably combined with the transmission 132; a belt137 to transmit rotating power via the pinion 133; driving pulleys 135,136 rotatably installed by the power transmitted from the pinion via thebelt 137, an idler pulley 134 rotatably installed for changing the pathof the belt 137 between the pinion 133 and driving pullys 135, 136 so asto increase the wrapping angle of the pinion 133; the belt 137transmitting the driving force from the pinion 133 to the driving pulley135, 136; a bracket 138 rotatably fixing the pinion 133, idler pulley134, and driving pulleys 135, 136 for forming them as one module; a pairof protuberances 138 a at both end sides of the bracket 138 to bepivotally combined with the track part 110 of the treadmill 100; and afixing plate 139 on a low side of the bracket 138 for fixing thetransmission 132.

In order to prevent the slip between the belt 137 and pulleys (includingpinion 133, idler pulley 134 and a pair of driving pulleys 135, 136),although not shown in the Figures, it is effective that grooves areperiodically formed at outside of the pulleys 133, 134, 135, 136, andthat protuberances for engaging with the grooves respectively areperiodically formed at one side or at both sides of the belt 137. Acommercially used V-groove type belt having protuberances on its oneside can be applied thereto through twisting the belt by 180 between thepinion 133 and the idler pulley 134 and between the idler pulley 134 andthe driving pulley 135.

Also, as shown in FIGS. 3 to 5 and 7, by the installation of the idlerpulley 134 in the bracket 138 for changing the path of the belt 137, thewrapping angle of the pinion 133 is increased more than 180° so thatprecise control of the rotation angle of the driving pulleys 135, 136can be realized by the increase of the driving friction therebetween.

A pair of the extendable rod 140 rotates together with each of thedriving pulleys 135, 136 fixed to the upper end thereof. Each extendablerod 140 includes a screw rod 142 having thread on its whole length, anda housing 141 having female thread for engaging with the thread of thescrew rod 142, and thus, each extendable rod 140 can become longer whenthe screw rod 142 is extruded from the housing 141 by relative rotationtherebetween, and become shorter when the screw rod is inserted into thehousing 141.

Herein, a hinge hole 141 a as a housing hinge is formed at the low endof the respective housing 141 for being pivotally combined with each ofsecond hinges 141 a of the track part 110. In order for the drivingpulleys 135, 136 and the bracket 138 integrally move together, thebracket 138 is fastened by nuts 142 b. That is, groove is formed betweenthe nut 142 b and the driving pulleys 135, 136 in the direction ofcircumference and the bracket 138 is inserted within the groove 142 a.

The drawing notation of 132 a is a bearing installation part supportingrotation of a rotating axis 132 b to connect the transmission 132 and apinion 133, and the drawing notation of 139 a is a bolt to fix thefixing plate 139 to the bracket 138.

Hereinafter, operation principle of the actuator 130 in accordance withone embodiment of the present invention is explained.

When the actuator motor 131 rotates in order to drive the contractedextendable rod 140 to be extended as illustrated in FIG. 5, the drivingtorque is transmitted from the actuator motor 131 to the pinion 133, andthe pinion 133 is driven to rotate counterclockwise. Accordingly, anidler pulley 134 connected by the belt 137 with the pinion 133 is drivento rotate clockwise, and simultaneously, a pair of driving pulleys 135,136 is driven to rotate counterclockwise. As one end 141 a of thehousing 141 is fixed to other component such as a support member 151 ora traverse member 153, the housing 141 is restricted not to rotate anylonger. Thus, as the driving pulley 135, 136 are driven rotatecounterclockwise, a pair of the screw rods 142 accordingly rotatetogether with the pulleys 135, 136 at the same angle, and thus, a pairof screw rods 142 is to be upwardly (142 c) extruded from the housing141 by the same length each other, whereby the length d of theextendable rod become longer as shown in FIG. 5.

Similarly, when the actuator motor 131 rotates in order to drive theextended extendable rod 140 to be contracted as illustrated in FIG. 3,the driving torque is transmitted from the actuator motor 131 to thepinion 133, and the pinion 133 is driven to rotate clockwise.Accordingly, an idler pulley 134 connected by the belt 137 with thepinion 133 is driven to rotate counterclockwise, and simultaneously, apair of driving pulleys 135, 136 is driven to rotate clockwise. As oneend 141 a of the housing 141 is fixed to other component such as asupport member 151 or a traverse member 153, the housing 141 isrestricted not to rotate any longer. Thus, as the driving pulley 135,136 are driven rotate clockwise, a pair of the screw rods 142accordingly rotate together with the pulleys 135, 136 at the same angle,and thus, a pair of screw rods 142 is to be downwardly (142 d) extrudedfrom the housing 141 by the same length each other, whereby the length dof the extendable rod become shorter as shown in FIG. 3

In the above manner, the actuator 130 can precisely control the lengthof a pair of the extendable rod simultaneously.

It is also possible that the actuator for controlling the inclination ofthe treadmill of the present invention can drive as a manner oftransmitting power from a motor to a screw rod of the extendable rodusing plural gears as shown FIG. 8.

Hereinafter, details of another embodiment of the present inventionincluding plural gears will be explained.

As illustrated in FIG. 8, an actuator 230 for controlling theinclination by using gears for transmitting the driving torque comprisesa driving unit generating the driving torque, and a pair of extendablerods 140 of which length are contracted and extended by the drivingtorque transmitted from the driving unit. Herein, in order to clarifythis embodiment, an explanation of the detailed structure describedabove on the extendable rod 140 is omitted as it is identical or similarto the foregoing embodiment.

The driving unit includes The driving unit has an actuator motor 131generating rotating force; a pinion gear 233 rotatably driven by theactuator motor 131; intermediate gears 234, 234′, 234″ engaging thepinion gear 233; a pair of driving gears 235, 236 fixed to rotatetogether with a screw rod 142 engaging the intermediate gears 234-234″and a bracket 138 formed for rotatably fix the gears 233, 234, 234′,234″, 235, 236 as one module.

In case that the pinion gear 233 is located in the center of bracket138, it is possible to arrange intermediate gear 126 symmetrically.However, in the case that the pinion gear 233 is not located in thecenter of bracket 138, such is not possible. For example, as shown inFIG. 8, when the pinion gear 233 is placed left from the center, oneintermediate gear 234 is installed between the pinion gear 233 and leftdriving gear 135, while three gears 234, 234′, 234″ are installedbetween the pinion gear 233 and right driving gear 136. That is, it isnot needed to set up the same number of left and right gear and it isenough to balance the number of the teeth of gears to be engaged eachother. When the number of left and right gears is different, a movingdirection of left and right screw rods 142 can be matched by means ofbalancing the number of intermediate gear. That is, when the number ofone side of intermediate gear 234 is odd, that of the other side ofintermediate gears 234-234″ should be odd, and when the number of oneside of intermediate gear 234 is even, that of the other side ofintermediate gears 234-234″ should be even.

Hereinafter, operation principle of the actuator 230 in accordance withanother embodiment of the present invention is explained.

In order to control the length of the extendable rod 140, as a actuatormotor 131 is driven to rotate, a pinion gear 233 also rotatesinterlocked with the actuator motor 131. Thus, one or severalintermediate gears 233, 233′, 233″ engaged with the pinion gear 233 alsorotate in the opposite direction, and the driving pulleys 235, 236engaged with intermediate gears 234 is also driven rotate. According tothe rotation of the driving gears 235, 236, a pair of the screw rod 142fixed to the driving gears 235, 236 respectively move up and down bybeing extruded from or being inserted into the housing 141 so that thelength of extendable rod 140 can be contracted or extended.

Furthermore, the mechanism of power transmission in accordance with oneembodiment of the present invention is not limited to the abovedescribed belt system as well as the gear system. The scope of thepresent invention includes a power transmission by driving the drivingmeans such as driving pulleys 135, 136 with a chain system, and alsoincludes the construction of which extendable rod comprises a rack gearengaging driving gears 235, 236.

On the other hand, the present invention provides with an inclinationcontrol device of treadmill using the above actuator for controlling theinclination of a treadmill. Hereinafter, details of an inclinationcontrol device of a treadmill in accordance with one embodimentreferring to FIGS. 9 to 13.

FIG. 9 is a perspective view illustrating the treadmill when theinclination of the track part is high position, and FIG. 10 is aperspective view illustrating the structure of treadmill without thedriving cover shown in FIG. 9. The treadmill 101 with the inclinationcontrol device in accordance with one embodiment of the presentinvention comprises a track part 110 on which user run or walk; a trackdriving unit 120 for driving the track belt 112 to rotate endlessly ofthe track part 110; an inclination control device to control theinclination of the track part 110 by including the actuator 130, theextendable rod 140 and a front support 150 to uphold the track part 110with controlling the inclination thereof; a rear support 160 to uphold arear part of the track part 110; and a column part 170 verticallyprotruded from the track part 110.

The track part 110 includes a main bracket 111 to cover the bottom sideof the track part 110; a footplate (not shown) installed in the mainbracket to uphold the load of user; a support frame (not shown)installed in the main bracket to support the footplate; a track belt 112installed to cover the upper and lower sides of the footplate forendlessly rotating; a side cover 113 to cover both sides of upper partof the main bracket 111; a plate 114 fixed to the upper side of thefront part of the main bracket 111 and having a hinge hole 114 a to bepivotally combined with each of the protuberance 138 a of the bracket138 of the actuator shown in FIG. 4; a first hinge plate 115 located atthe lower side of the main bracket 111 to pivotally combined with theend of the support member 151; a fixing plate 116 located at the upperside of the main bracket 111 for easily combining the column part 170.

The track driving unit 120 includes a track driving motor 121 generatingthe rotating power driving the track belt 112 of the track part 110, aconnection belt 122 transmitting power of the track driving motor 121, adriving roller 123 connected with the connection belt for being drivento rotate by the track driving motor 121, an idler roller 124 located atthe rear part of the track part 110, and a driver unit cover 125 forpreventing the undesirable dusts or particles from entering into thetrack driving motor 121.

The front support 150 includes a pair of support members 151 pivotallyconnected to each of the first bracket 115 located at both sides of thelower part of track part 110, a roller 152 rotatably combined with theend of each of the support member 151 so that the end of the supportmember 151 can smoothly slide against the ground. And the support member151 includes a traverse member 153 to connect the both support members151 each other. Herein, a first hinge 151 a is formed at the pivotallyconnected point between the support member 151 and the first bracket 115of the track part 110.

The rear support 160 has contact portions made of rubber material forpreventing the unexpected slide between the rear support 160 and thecontact portion.

The column part 170 includes a column 171 upwardly stretching from thetrack part 110 by combining with the fixing plate 116, a handle attachedto the other end of column 171, and a control panel 173 combined withthe end of the handle for inputting the exercise program and displayingexercise information.

The inclination control device includes the actuator 130 forsimultaneously controlling the length of the extendable rod 140 by thesame amount, the expandable rod 140 as described above, and a frontsupport 150 for upholding the front part of track part 110.

The actuator 130 is structured as illustrated in FIG. 3 or FIG. 7 andabove mentioned. How to install the actuator 130 in a treadmill is asfollow.

As illustrated in FIG. 13, an inclination control device of treadmill ofthe present invention can efficiently prevent its members 110, 151, 141from being concentrated by load from a user due to three-link trussstructure of which three hinges 151 a, 141 a, 138 a are formed asrotatable.

Also, by supporting both sides of the track part 110 with two extendablerods, an inclination of the track part 110 in the width direction can beprevented thereby preventing the fluctuation or unbalance thereof in thewidth direction.

Comprised as above mentioned, the operation mechanism of the inclinationcontrol device of the treadmill can be easily understandable referringto that of the foregoing actuator in FIG. 3 and FIG. 4. A difference ofrotating direction of the actuator motor 131 makes a pair of screw rods141 be extruded from the housing 141 by the same length so that theinclination of the track part 110 can be precisely controlled. FIG. 12illustrates the situation when the length d of extendable rod 140 getsshortest, and thus, the downward inclination of the track part 110 isrealized within the range between −10° and 0°

Referring to FIG. 12, in case that the load Fp due to a user's exercisethereon is applied on the front part B of track part 110 as indicated inFIG. 12, the reaction force Fa on the extendable rod 140 and thereaction force Fs on the support member 151 can be calculated asfollowing equations 2 and 3.Fs=Fp×(L2/L1)  EQUATION 2Fa=Fp×(L4/L3)  EQUATION 3

Therefore, different from the reaction force for the inclination controldevice of a conventional treadmill (see equation 1), the reaction forceFa on the extendable rod 140 in the axial direction thereof is came tobe reduced rather than be increased. Furthermore, any moment is notapplied on the extendable rod, since both ends of the extendable rod 140are formed as the rotatable hinges 138 a, 141 a. In view that a membercame to be broken due to the repeated bending fatigue loads, theactuator 130 can have almost permanent life span because any moment isnot applied on the extendable rod 140. As the moment and the reactionforce Fa of the extendable rod 140 are minimized, it is possible todesign the extendable rod to have a minimized diameter, thereby alsorealizing the smaller capacity of the actuator motor as well as thereduced weight of the extendable rod 140 (i.e., the housing 141 and thescrew rod 142) Accordingly, energy consumption required to drive and tomanufacture the actuator 130 can be also reduced.

In addition, by letting the second hinge 141 a far apart from the trackpart 110, as the reaction force on the extendable rod 140 in the axialdirection thereof can surprisingly be reduced, when the length of thesupport member 151 is assumed to be L5, it is more desirable that thelength of L3 is longer than 0.5*L5.

As above explained, The present invention provides with an actuator forinclination controlling of treadmill, which comprises: a motor, a pinionrotating with power of the motor, a belt for transmitting power from themotor, a pair of driving pulleys rotatably engaged with the belt, a pairof the screw rod combined with the driving pulley on its one end, afemale screw engaging a screw thread of the screw rod, a housingattached to the screw rod by the female screw so that it facilitatesinclination control of a track of the treadmill.

In order to maintain the track part stable during a user's exercise onthe track part, a pair of the extendable rod including the screw rod andthe housing can be contracted or extended by the same length so that thetreadmill can be easily and precisely controlled.

In addition, as the present invention provides with an inclinationcontrol device of treadmill using the actuator supporting both sides oftrack part with a pair of the extendable rods, a user can run or walk onthe track part 110 without an inclination in the width direction whichcauses a user feel to unstable and unsafe.

The present invention also can save manufacturing cost and enhancedurability surprisingly because the load can be effectively diverged andthe moment on the extendable rod is removed by constructing one or apair of three-linked truss structure of which hinges are all rotatablerelative to the near members. Also, the actuator according to thepresent invention can save power consumption for driving andmanufacturing cost.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

On the other hand, although the actuator 130 using belt 137 fortransmitting the driving toque is described above as one embodiment ofthe present invention, any actuator capable of simultaneouslycontrolling a pair of the extendable rod 140 is within the scope of thepresent invention. Also, the inclination control device having a pair ofthe extendable rod 140 for achieving three hinges 138 a, 141 a, 151 forthree-linked truss structure is described above as one embodiment of thepresent invention, an inclination control device only having oneextendable rod 140 is also within the scope of the present invention.

1. An actuator for controlling the inclination of the track part of atreadmill comprising: a motor; a pinion rotatably driven by the motor; abelt formed to transmit the driving force from the pinion; a pair ofdriving pulleys engaging with the belt so as to receive the drivingforce from the pinion; a pair of screw rod combined with each of thedriving pulley for rotating together with each of the driving pulley;and a pair of housings having female thread for engaging with each ofthe screw rod; wherein a pair of screw rods are simultaneously extrudedfrom or simultaneously inserted into each of the housing by the samelength.
 2. The actuator for controlling the inclination of the trackpart of a treadmill as claimed in claim 1 further comprising: at leastone idler pulley engaging with the belt; wherein the belt is engagedwith the pinion, the idler pulley, and the driving pulleys fortransmitting the driving force from the pinion to the driving pulleys.3. The actuator for controlling the inclination of the track part of atreadmill as claimed in claim 1, wherein the pinion, the idler pulley,and the driving pulleys has at least one groove on their sides so as toengage with the protuberances periodically formed on the belt.
 4. Theactuator for controlling the inclination of the track part of atreadmill as claimed in claim 2 further comprising: a bracket forrotatably fixing the pinion, the idler pulley and the driving pulleys;and bracket hinges formed at the both sides of the bracket; housinghinges formed at each of the housings.
 5. An inclination control devicefor a treadmill having at least one track part comprising: at least onesupport member pivotally connected with at least one first hinge at thetrack part for extending from the track part to the ground; and at leastone extendable rod pivotally connected with at least one second hingewhich moves together with the support member, and pivotally connectedwith at least one third hinge of the track part which is located apartfrom the first hinge at the track part; wherein, the inclination of thetrack part is controlled by the extension or the contraction of theextendable rod.
 6. The inclination control device for a treadmill asclaimed in claim 5, wherein the support members are formed as a pair forpivotally being connected with a pair of the first hinges at the trackpart, and the extendable rods are formed as a pair for pivotally beingconnected with a pair of the third hinges at the track part.
 7. Theinclination control device for a treadmill as claimed in claim 6,wherein a pair of the support members include a traverse member whichconnects the support members each other, and the second hinges areformed as a pair at the support members or at the traverse member forpivotally being connected with a pair of the extendable rods.
 8. Theinclination control device for a treadmill as claimed in claim 7,wherein a pair of the extendable rods include a pair of housings havinga housing hinge respectively for being pivotally connected with each ofthe second hinge, and having female thread; and a pair of screw rodsengaging respectively with the female thread of each of the housing soas to be extruded from or inserted into each of the housing by relativerotation therebetween; and, further comprising: a pair of drivingpulleys combined with each of the screw rod for rotating together withthe screw rod; a belt engaging with the driving pulleys; a pinionengaging with the belt for transmitting a driving force via the belt tothe driving pulleys; a motor for making the pinion rotate; and a bracketfor rotatably fixing the pinion, and the driving pulleys, and having apair of bracket hinges on its both sides to be pivotally combined witheach of the third hinges; wherein one of the first hinges, one of thesecond hinges, and one of the third hinges form hinges of three-linkstructure.
 9. The inclination control device for a treadmill as claimedin claim 8, wherein the screw rods integrally rotate with each of thedriving pulley respectively.
 10. The inclination control device for atreadmill as claimed in claim 8, further comprising: at least one idlerpulley rotatably fixed to the bracket for engaging with the belt;wherein the belt is engaged with the pinion, the idler pulley, and thedriving pulleys for transmitting the driving force from the pinion tothe driving pulleys.
 11. The inclination control device for a treadmillas claimed in claim 10, wherein the pinion, the idler pulley, and thedriving pulleys have at least one groove on their sides so as to engagewith the protuberances periodically formed on one side of the belt. 12.The inclination control device for a treadmill as claimed in claim 8,further comprising a roller formed at the end of each of the supportmember which is contact with the ground.
 13. The inclination controldevice for a treadmill as claimed in claim 8, wherein the second hingesare formed within the range between 0.1 L to 0.5 L from one endcontacted with the ground, when the length of the support member is L.14. The inclination control device for a treadmill as claimed in claim8, wherein a pair of the extendable rods include a pair of housingshaving a housing hinge respectively for pivotally connecting with eachof the second hinge, and having female thread; and a pair of screw rodsengaging respectively with the female thread of each of the housing soas to be extruded from or inserted into each of the housing by relativerotation therebetween; and, further comprising: a pair of driving gearscombined with each of the screw rod for rotating together with the screwrod; at least one pair of intermediate gears engaging with the drivinggears; a pinion gear engaging with the intermediate gears fortransmitting a driving force via the intermediate gears to the drivinggears; a motor for making the pinion gear rotate; and a bracket forrotatably fixing the pinion gear, the intermediate gears and the drivinggears, and having bracket hinges on its both sides for being pivotallyconnected with each of the third hinges; wherein one of the firsthinges, one of the second hinges, and one of the third hinges formhinges of three-link structure.
 15. An inclination control device for atreadmill having at least one track part, comprising: a pair of supportmembers pivotally connected with a pair of first hinges at the trackpart for extending from the track part to the ground; a pair of housingshaving a housing hinge respectively for being pivotally connected with apair of second hinges at the support members, and having female thread;a pair of screw rod engaging respectively with the female thread of eachof the housing so as to be extruded from or inserted into by relativerotation therebetween; a pair of driving pulleys combined with each ofthe screw rod for rotating together with the screw rod; a belt engagingwith the driving pulleys; a pinion engaging with the belt fortransmitting a driving force via the belt to the driving pulleys; amotor for letting pinion rotate; and a bracket for rotatably fixing thepinion and the driving pulleys, and having a pair of bracket hinges onits both sides to be pivotally combined with a pair of the third hingesat the track part; wherein the third hinges are apart from the firsthinges respectively, and wherein one of the first hinges, one of thesecond hinges and one of the third hinges form a three-linked structure.16. The inclination control device for a treadmill as claimed in claim15, wherein the screw rods are integrally rotate with each of thedriving pulley respectively.
 17. The inclination control device for atreadmill as claimed in claim 15, further comprising: at least one idlerpulley rotatably fixed to the bracket for engaging with the belt;wherein the belt is engaged with the pinion, the idler pulley, and thedriving pulleys for transmitting the driving force from the pinion tothe driving pulleys.
 18. The inclination control device for a treadmillas claimed in claim 17, wherein the pinion, the idler pulley, and thedriving pulleys have at least one groove on their sides so as to engagewith the protuberances periodically formed on one side of the belt. 19.The inclination control device for a treadmill as claimed in claim 15,further comprising a roller formed at the end of each of the supportmember which is contact with the ground.
 20. The inclination controldevice for a treadmill as claimed in claim 15, wherein the second hingesare formed within the range between 0.1 L to 0.5 L from one endcontacted with the ground, when the length of the support member is L.